Gantry for computed tomography

Abstract

An x-ray source and a detector array are mounted on opposite sides of a generally horizontally extending longitudinal axis of a rotating base. The rotating base is journaled on a tiltable frame. The frame is supported on curved tracks for tilting by translating along a curved path about a fixed transverse virtual axis of rotation which is perpendicular to and intersects the rotational axis of the rotating base. Tilting the frame permits making an x-ray scan through a layer of a patient which is at an acute angle relative to the longitudinal axis. The azimuth drive for the rotatable frame utilizes a toothed belt. A self-acting friction brake is provided for constraining the rocking base. A hoist is provided for making installation and removal of the x-ray source convenient.

We claim: 
     
       1. X-ray tomographic apparatus comprising: frame means and means for supporting said frame means for tilting about a laterally directed axis between opposite angles with respect to vertical,   rotatable base means supported for rotation relative to said frame means about a longitudinal axis which is perpendicular to and intersects said laterally directed axis,   x-ray source and x-ray detector means mounted on said rotatable means on opposite sides, respectively, of said longitudinal axis for jointly orbiting about an examination body which may be disposed along said longitudinal axis, and   means for tilting said frame means about said laterally directed axis, and   hoist means mounted to said frame means, said hoist means being constructed and arranged for enabling means which are mounted to said rotatable base to be coupled with and supported by said hoist means.   
     
     
       2. The apparatus as in claim 1 wherein said hoist means comprises: a generally vertically disposed jib column mounted to said frame means at a side thereof, said column being mounted for rotation about its axis, and   an arm extending radially and generally horizontally from said column, said arm being swingable with said column over and away from the orbital path of said x-ray source and said detector means.   
     
     
       3. A tilting gantry for x-ray tomography comprising: a pair of generally L-shaped members spaced apart from each other in the transverse direction, each of said members comprising an upstanding leg portion and an angularly related base portion, each of said base portions having a lower edge which is curved convexly downwardly,   a downwardly convex curved track fastened to each of said base portions, the radii of curvature of each of said tracks passing through a virtual transversely extending axis which is above said tracks,   a stand fixed adjacent each of said tracks,   first and second sets of rollers supported on respective stands for rotation and said tracks being supported on said sets of rollers, respectively, for translating thereon along a curved path about said virtual transverse axis,   support means spanning between and connected with said upstanding portions of said L-shaped members,   pulley means journaled in said support means and rotatable about a longitudinally directed axis which intersects and is perpendicular to said virtual transverse axis, said pulley means being open within its circumference for permitting an examination subject to be translated along said longitudinal axis,   a rotatable base fastened to said pulley means for rotation therewith,   x-ray source and x-ray detector means mounted to said rotatable base on opposite sides of said longitudinal axis for orbiting about said axis when said base is rotated,   means for driving said pulley means rotationally,   means for moving said tracks on said rollers to effect tilting of said L-shaped members, and   hoist means comprising an arm supported for swinging in a substantially horizontal plane and means for supporting said arm from said L-shaped member, said arm being swingable substantially over at least a portion of the orbital path of said x-ray source and detector means to facilitate coupling said source or means with said arm.